1. Field of the Invention
Apparatuses and methods consistent with the present invention generally relate to an adjustable chaotic signal generator using pulse modulation for ultra wideband (UWB) communications and a chaotic signal generating method thereof. More particularly, apparatuses and methods consistent with the present invention relate to an adjustable chaotic signal generator using pulse modulation for UWB communications, which enables a plurality of users to wirelessly communicate at the same time within a specific wireless communication range by generating a chaotic signal that can be split to a plurality of channels.
2. Description of the Related Art
In addition to Bluetooth, wireless communication schemes using the ultra wideband (UWB) frequency band of 3.1˜5.1 GHz are under development, one of which utilizes a chaotic signal in accordance with IEEE 802.15.4a Standard.
IEEE 802.15.4a, which is a “location-recognition low-power sensor network standardization group”, is a next generation communication technology having a location recognition function and a low power consumption based on a combination of 802.15.4 (ZigBee) and 802.15.3 (UWB).
A chaotic signal modulation has been suggested to realize low power consumption. The chaotic signal modulation can be designed in a simplified radio frequency (RF) hardware structure and does not need circuits such as a voltage-controlled oscillators (VCO), a phase-locked loop (PLL) circuit, a mixer and so forth, that have been required for a conventional wireless communication system. Accordingly, the use of chaotic signal modulation can reduce power consumption to 10 mW which is merely one third of conventional power consumption.
An aspect of chaotic signal modulation is a chaotic signal generator which generates an UWB chaotic signal. A conventional chaotic signal generator generates a chaotic signal in the UWB of 3.1˜5.1 GHz. The generated chaotic signal is modulated to a chaotic carrier using ON and OFF according to on-off keying (OOK).
However, the chaotic signal, which is generated at the chaotic signal generator, is shaped into a single signal having the entire UWB frequency band. Thus, when a plurality of users uses wireless devices within a specific wireless communication range, interference occurs because the same channel is being used. As a result, only one wireless device can transmit and receive radio signals in the specific wireless communication range at a time. That is, frequency division multiplexing (FDM), which enables users to communicate in a certain wireless communication range using multiple frequency channels, is infeasible.
Therefore, what is needed is a method for enabling a plurality of users to wirelessly communicate in a specific wireless communication range at the same time in accordance with FDM by splitting the chaotic signal generated at the chaotic signal generator into multiple frequency bands, that is, into multiple channels.